It is said to have started operating a vehicle equipped with a translucent liquid crystal display in the window on Line 6 of the Beijing Subway, China. Reportedly, this display was introduced by the Beijing subway as a pilot. As you can see from the video, it shows the train location and route network, a 3D station diagram, the location of service facilities in the station, and a colorful 3D animation.
Of course, the transparent display itself is not that new technology. In addition, there may be concerns that you will not be able to enjoy the scenery outside the car window properly, but there may be less dissatisfaction because the scenery such as underground is often monotonous. In addition, if it is used as an advertising space rather than simply displaying operation information, it may lead to new revenue expansion for railroad operators. Related information can be found here .